(in stories) a frightening creature that is a dead person who has been brought back to life, but without human qualities. Zombies are not able to think and they are often shown as attacking and eating human beings:

a dead person who is believed, in some Caribbean religions, to have been brought back to life by magic

informal disapproving a person who has no energy, seems to act without thinking, and does not notice what is happening: He’s just a zombie sitting in front of the TV all day.